The field of the invention relates generally to sensor devices and methods and, more particularly, sensing current through a conductor.
At least some known utility meters are used to measure electricity supplied from a power source to a user. To enable an amount of energy supplied to a user to be accurately measured, utility meters often include one or more sensor devices to sense current flowing through a conductor between the power source and the user. When included in a utility meter, the sensor device is intended to function accurately over an operating range of voltages and/or currents.
Various types of known current sensor devices are used in utility meters. For example, at least some known transformer sensor devices include a magnet core with magnet wire wound thereon to sense current flowing through a conductor. Current sensor devices including transformers, however, are generally known to be bulky and expensive. Current sensor devices with magnetic cores may be vulnerable to external magnetic fields. Exposure to external magnetic fields reduces the accuracy of magnetic core current sensor devices, and in some cases the accuracy may be reduced to the point where the current device registers only as little as 8% of the current that the current device should be sensing. Temperature cycles may also affect the magnetic core of current sensors and cause magnetic drift which reduces the accuracy of the current sensor.
Another example of a known current sensor device is a Rogowski coil. Rogowski coils include a coil and are generally smaller than transformer sensor devices. However, Rogowski coils are known to provide only limited accuracy during low current and/or high current conditions over a range of voltages. As a result, during manufacturing, utility meters with known Rogowski coils are often subjected to multiple calibration processes to minimize the effects of these inaccuracies. Although these repeated calibration processes may reduce the inaccuracies of such sensor devices, the processes also increase manufacturing times and costs of the utility meters.